Experimental Chlamydia trachomatis infection causes apoptosis in human sperm.

BACKGROUND: Chlamydia trachomatis is responsible for a widespread sexually transmitted infection. In men, it is associated with a wide clinical spectrum causing infertility. Furthermore, C. trachomatis serovar E infection decreases motility and increases the number of non-viable sperm. No other effects of C. trachomatis have been reported on sperm despite the crucial role of DNA integrity for sperm function. The aim of this study was to investigate the effects of C. trachomatis on sperm apoptosis. METHODS: Sperm from eight normozoospermic men were incubated with increasing concentrations of C. trachomatis serovar E elementary bodies (EB) for 6 and 24 h. Sperm were then collected to evaluate phosphatidylserine (PS) membrane translocation and DNA fragmentation by Annexin V-propidium iodide staining, TUNEL assay and flow cytometry. RESULTS: After 6 h of incubation, C. trachomatis had no effect on the percentage of sperm showing PS externalization. However, a significant effect on this parameter was observed after 24 h. C. trachomatis also significantly increased the number of sperm with DNA fragmentation both after 6 and 24 h of incubation. CONCLUSIONS: C. trachomatis causes sperm PS externalization and DNA fragmentation. These effects may explain the negative direct impact of C. trachomatis infection on sperm fertilizing ability.

Human follicular fluid stimulates the sperm acrosome reaction by interacting with the gamma-aminobutyric acid receptors.

OBJECTIVE: To evaluate whether gamma-aminobutyric acid receptors are involved in human sperm acrosome reaction induced by the follicular fluid (FF). DESIGN: Random selection of normal sperm samples. SETTING: Normal men in an university clinic of andrology. PATIENT(S): Men with normal sperm analysis parameters. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): Acrosome reaction on motile spermatozoa. RESULT(S): Follicular fluid stimulated the acrosome reaction dose-dependently. The effect of a maximally effective concentration of FF (30%, vol/vol) was significantly suppressed by bicuculline, a GABAA receptor antagonist, and saclofen, a GABAB receptor antagonist, added concomitantly. Each of the two antagonists used alone was devoid of effect. Because the GABAA receptor is linked to the chloride channel, we tested whether picrotoxin, a blocker of this channel, could modulate the effects of the FF. Picrotoxin alone did not have any effect on the acrosome reaction induced by the FF, whereas it had a significant suppressive effect if coincubated with saclofen. The acrosome reaction induced by the FF was also inhibited by picrotoxin plus verapamil, a calcium channel blocker, whereas verapamil alone had no significant effect. This suggested that both chloride and calcium ions mediated the acrosome reaction induced by the FF. CONCLUSION(S): The simultaneous blockade of GABAA and GABAB receptors suppressed the acrosome reaction induced by the FF. This finding suggested that GABA receptors play a physiologic role in sperm activation and shed further light on the mechanism of FF action on human sperm acrosome reaction.